Tuesday, June 6, 2017

Scientists Digitize Bernie's Shoes

Wearing white sneakers, a cowboy hat and overalls, Bernie Fowler walks into Maryland's Patuxent River every June to see how deep he can go and still see the tops of his shoes. As a young man he could see his feet on the river bottom as he stood chest-deep to net blue crabs. Now in his nineties, he ventures into the river to assess the water clarity. Fowler has been collecting this data point for the past 29 years and counting, calling it "sneaker depth."

Scientists make precise measurements of water clarity from satellite data, but the calculations can be complex and hard to explain to people outside the discipline of oceanography. Now NASA is adopting Fowler's sneaker idea to communicate satellite measurements of water clarity, enabling the observations to be shared easily with interested the general public, local governments or anyone who is interested. NASA scientists calling this algorithm "Fowler's Sneaker Depth" -- the depth of water, in meters, at which a person can no longer see their white shoes. The study was published in the April 2017 edition of The Optical Society journal Optics Express.

Bernie (center) leading a wade-in on the Rhode River

"When you talk to people about the chemistry of the river with scientific words like eutrophication, it goes in one ear and out the other," said Fowler. "If you put on white sneakers and wade out in the river until you can't see your feet, that gives you pretty good understanding of what's going on." On June 11, 2017, Fowler, his family, friends and community will wade into the Patuxent River at Jefferson Patterson Park and make sneaker depth measurements for the 30th consecutive year.

Scientists sitting in an ocean ecology lab focus on accuracy, said Lachlan McKinna, an oceanographer at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and one of the study's authors. "But we sometimes need better ways to communicate with the general public."

Ben Crooke, a 17-year-old NASA summer intern, helped derive Fowler's Sneaker Depth as the first author of the paper. Crooke spent part of his summer analyzing Fowler's data and satellite imagery to understand local trends in water clarity.

Crooke and the team looked at data from the Aqua satellite's onboard instrument,the Moderate Resolution Imaging Spectroradiometer, or MODIS. The instrument measures different colors of light, or wavelengths, that are reflected from matter suspended in the water. They specifically looked at the amount of red light reflected of off floating particulates and sediments that make the water appear murky.

The team then developed a mathematical model to relate the amount of red light reflected, as measured by MODIS, with the sneaker depth, as physically measured by Fowler in the Patuxent River, for the years 2002 to 2016.

Bernie was a local real estate developer who got into politics late in life. He still lives in the area, a little up the Bay at Dare's Beach.

It's interesting, and a little backwards, that scientists are taking complex measurements from space and turning them in to sneaker equivalents.